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Hardware

Manually-Confirgured Software RAID Under NT? 31

Posted by Cliff from the funny-how-it-used-to-mean-"bug-spray" dept.
Mandoric asks: "I recently had a RAID-0 array die due to the controller refusing to recognize it as anything but a pair of single drives. Are there any software RAID programs (preferably under NT, as it's an NTFS partition I'd be restoring) that allow manual entry of a preexisting array's stripe size, rather than forcing all stripe data to be rewritten before reading from an array? Or ways to modify the volume data of an existing program to do this?" Are there decent RAID tools, for either NT or for Unix, that will allow one to recover from errors such as this?
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Manually-Confirgured Software RAID Under NT? More

Manually-Confirgured Software RAID Under NT?

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  • This is one of the several reasons why software RAID, especially under NT is a bad idea. While there may be an obscure utility out there, chances are slim. Your likely only hope is going to be a disk editor.

    With RAID 0, software or hardware, your best solution is going to be tape. But, it sounds like you don't have that option. Treat the incident as a learning experience and move on.

    • Re:One reason. (Score:2, Informative)

      by dhopton ( 252883 )
      This person wasnt using software. They were using Hardware based soltuon which subsequentially broke, and he's looking at a software based soltion to recover the data.
  • NT4 and above have always supported software RAID, most commonly RAID-0, and in the server editions RAID-1 too (I think it did some others, I'm not sure).

    Neither of these will help since you are having to recover the data, and even so the hardware controller may have a differant format to the NT one etc (same goes for any controller).

    I think the best solution, if you dont have a backup is talk to the people like Ontrack - they can recover almost anything.

  • Recovering broken RAID (Score:4, Informative)

    by sofar ( 317980 ) on Tuesday February 19, 2002 @12:40PM (#3032303) Homepage
    Well, it's probably not the easiest approach but one that is definately looking into IMHO:

    - pop the disks into a linux or un*x system on a free controller port

    - pop in an extra empty disk to salvage the data to. preferable larger than both disk together ;-)

    - try to figure out the block size of the stripes (usually a multiple of 512 bytes)

    - write a simple script that reads block n from broken RAID disk 1, and writes it to block 1 in the empty disk, then block 1 from broken RAID disk 2, to block 2 in the empty disk (ask your local unix guru)

    You can fiddle with mount, df and cat /dev/hd?? > hexdump to see how data is arranged on the disks. Hardware RAID does usually not put special data blocks on the disks that make it unaccessible for these tools.

    As an example, I run a software RAID and unmounted it cleanly, then remounted only one of both disks at the same point (so without the mirroring). Worked like a charm, also a nice way to continue working when one disk completely fails or you want to make copies fast ;-)

    good luck

  • What hardware? (Score:5, Insightful)

    by bedessen ( 411686 ) on Tuesday February 19, 2002 @01:55PM (#3032771) Journal
    You didn't mention anything about your hardware, but I had the exact same thing happen to me with the Highpoint 370 controller on a KT7-RAID motherboard. I rebooted one day to find that the HPT BIOS would say only "broken stripe." I figured my NTFS partition was toast. But there is a utility, raidrb, which I think is written by either Via or Highpoint. Anyway you just boot from a floppy and run it and it "reassures" the controller that the stripe is really ok.

    http://download.viahardware.com/faq/kg7kr7/downloa ds/utils/raidrb.zip [viahardware.com]

    There is some discussion of other methods to try if this one does not work in the Raid section on Paul's KT7 page. (Google search for "kt7 faq" for the url.)

    • ... Yep, this was the same controller, on an 8K7A+., Unfortunately, the util didn't work, but it did get it to the point where it was recignized as stiping properly... Ah well, thanks anyway. If something else major wasn't borked, that would have fixed it...

  • Raid 0? (Score:3, Informative)

    by EvilOpie ( 534946 ) on Tuesday February 19, 2002 @01:58PM (#3032791) Homepage
    I am curious as to what the job of the server that the raid card was in was. After all, if he truly meant Raid 0, then that is striping without fault tolerance. If you had one drive fail, then the whole raid array would fail and he'd be in the same situation. Now there is an advantage in speed when it comes to drive access, but still, a single disk failure would take out the whole array. That is not unlike what happened here in that the raid array failed when the controller bombed.

    That being the case, he should have backups somewhere to restore the data from. I wouldn't trust anything mission critical to a raid 0 array. Besides, when the controller went down, who's to say that it didn't basically shred the data on the disk apart? If the data is being spread across 2 disks, and now the computer sees them as two separate disks instead of one larger disk, then the data on the two disks is probably toast to begin with. (with the exception of going to those companies that do sector by sector data recovery from a hard drive for ungodly sums of money)

    I guess the only thing I could suggest is to redo the server with Raid 1 minimum, and hope that your backups are good. There's no telling what that raid card did to your system when it failed.
    • He never said it was a server (although it may have been). It could have been a workstation that needs fast drive access. There are probably a number of uses for this, the one that immediately comes to mind is video capture. Video capture needs huge amounts of space, and very high sustained write throughput.

  • Veritas can do this (Score:4, Informative)

    by duffbeer703 ( 177751 ) on Tuesday February 19, 2002 @02:03PM (#3032822)
    Veritas Volume Manager for NT/2000 can do this.

    http://www.veritas.com/products/category/Product De tail.jhtml?productId=volumemanagerwin

    Only one problem. It is very expensive.
    • Windows 2000 comes with Vetrias Volume Manager "lite" for lack of a better term, known as the Logical Disk Manager Service. It's what provides the software RAID functionality. (Raid 0 IIRC in Pro, perhaps RAID 0 and also RAID 1 in Server+)

      The real version adds more stuff though.

  • Resource Kit (Score:2, Interesting)

    by Dunkirk ( 238653 )

    There was a resource kit utility to open up software RAID sets and fix them under NT/2000. I have played with it only to see what it does, and that was years ago. It was made for exactly what you're talking about doing.

    However...

    I don't think that's a good idea. I don't think you're going to get done in software what the hardware was doing for you. If the data is truly sacred, I think one of the other posters was correct: go to a data-recovery service and let a professional do it. If the data is only partly holy, then try finding a utility from the controller maker.

    dk

  • Because your array was in hardware raid you may need to replace the the controller card. It may just get picked back up as it was if the drives or data didnt sustain any dammage.

    use ghost or dd to back the contents of the drives up anyways incase the hardware solution has to re initialize the array from scratch.

    you maybe able to find a controller that will work with software that can help fix your problem but i wouldnt count on software raid doing it.

    shoulda used raid 0+1 maybe even 3 or 5

  • Here is an article (Score:3, Informative)

    by Aknaton ( 528294 ) on Tuesday February 19, 2002 @07:59PM (#3035291)
    on Tom's Hardware entitled: "RAID without additional hardware: Do It Yourself With Windows 2000"

    http://www4.tomshardware.com/howto/01q3/010906/i nd ex.html
  • This sounds like a issue with the hardware, most likely one that tech support will tell you how to fix, or if not, how to recover your data. At least you would hope they would know...
  • Wondering what the hell all of this RAID stuff is about, don't worry...your plants are safe!!! To calm you further, I thought I would be generous and give you a brief description of the various levels.

    But first, in case you road the "short bus" to school, we are not discussing the bug spray [killsbugsdead.com] or what the Feds do to your dope stash... RAID is a commonly used acronym for Redundant Array of Inexpensive Disks!!!

    Now, on to the various levels of RAID... The most common are as follows:

    o RAID 0 : Striping without redundancy (a.k.a. no fault tolerance)
    o RAID 1 : Transparent Mirroring
    o RAID 3 : Striping with Parity for High Data Transfers
    o RAID 4 : Striping with Parity for High Data Transfers
    o RAID 5 : Striping with parity for High I/O transaction rates

    • So if I have a raid 1 setup, that is the exact same stuff on both disks that I would have on a single disk, right? So if I decided to pop out one disk and put it into another box, it could be used normally, i.e. there isn't weird stuff on the disk because it's raid 1, right?
      • To my understanding, that is completely correct...

        A level-1 RAID array provides a mirror, or exact copy, of the live disk being written to and accessed by the users of the device. Thus, this is what provides the fault tolerance...

        If either disk fails, the users' data remains viable and their is no break in service!!!

        One aspect that I didn't cover in my original post was the number of disks required to affect the various levels of RAID:

        RAID 0 - Minimum of two drives
        RAID 1 - Minimum of two drives
        RAID 3 - Minimum of three drives
        RAID 5 - Minimum of three drives

        Additionally, there is an obvious consequence to having implemented a RAID array, which is the sacrifice of viable disk space. Because the drives store redundant data (either through mirroring or striping w/ parity), the below formulas must be used to determine the amount of available disk space:

        RAID 0 - No loss of disk space due to lack of redundancy (striping only)
        RAID 1 - Total disk space / 2
        RAID 3 - Size of smallest drive in array = N, total space = (# of drive - 1) * N
        RAID 5 - Size of smallest drive in array = N, total space = (# of drive - 1) * N

        I hope this helps...for further information I would suggest a simple search on Google [google.com]!!!

  • with Linux? (Score:2, Interesting)

    by chtephan ( 460303 )
    How does NT stripe? Some blocks on the first disk, some blocks on the next, some on the first, ... without any metadata at the beginning?

    Then this should be fairly easy. Find out which block size is used, boot from some linux rescue CD and initialize a software raid without persistent superblock. After that you should be able to mount the NTFS partition (at least for reading) and copy everything off it.

    If there is some data before the actual partition, you can use the loop device with the offset parameter to skip the junk.

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